1. Field of the Invention
The present invention relates to an apparatus to prevent accidental transfusion of mismatched blood types from a blood bag containing pre-typed blood to a patient of a different blood type. More particularly, each of a connected series of decreasingly sized individual cannula spikes is configured to be matingly received by, and uniquely coded to, its unique and matching female receptacle which is permanently attached to the blood bag.
2. Description of the Prior Art
Various inventions are known which have been proposed to help prevent the fatal effect of infusion of an improperly matched blood type to a patient. Each of such inventions have major drawbacks which generally stem from a requirement that the healthcare provider take positive, cognitive actions to avoid an improper match. The prior inventions, although serving to alert or remind the healthcare provider that a mismatch can occur, generally do little to actually physically prevent and actively discourage an incorrect connection between a typed blood bag and a cannulated patient otherwise effected by an unobservant or persistent healthcare provider.
To appreciate the disadvantages of the known art, an understanding of the blood typing system and the elements common to all patient cannulations is necessary. Typically, when blood is donated, the blood is prepared and typed according a universal blood typing system: A, B, AB, and O wherein AB is a universal recipient and O is a universal donor. The rh-factor of blood is also typed as positive (+) or negative (-). Hence, each bag may contain any one of eight different blood types and is so labelled for future use and for cold storage. This critical point provides the first opportunity to modify the blood bag to prevent future mistakes.
When a patient is in need of blood, the patient is also blood typed, and may be labelled too, whether by bracelet or other means. However, not all patients must receive an exactly matched blood type. Some blood types are acceptable to some patients in accordance with the universal blood typing system: AB patients may receive all blood types, AB, A, B or O; A patients may receive A or O type blood; B patients may receive B or O type blood; but, O patients may receive only O. Moreover, mismatched rh-factors (+ instead of -, and vice versa), may be critical to the welfare of the patient, nevertheless, often are not critical. Therefore, an rh-factor mismatch may be voluntarily risked in certain emergency cases, so long as the proper blood type is available and chosen.
Based upon such information, the appropriately labelled blood bag is matched to the patient. Each bag is typically provided with a pilot tube depending from a lowermost edge, which is provided with a puncturable diaphragm. A cannula, typically having a bag end attached to a hollow spike for puncturing the diaphragm and a patient end adapted for venous infusion, is provided as a separate unit which, when inserted into both bag and patient, allows the bag to be hung on an I.V. pole and allow the red blood cells to infuse by gravity into the patient.
When simple labelling techniques are used to identify blood bags, the ease of making a mistake is obvious. By merely misreading a label, the wrong blood bag may be chosen by the health care provider even when both donor blood and recipient patient are correctly typed. Statistics show that this type of accident is the most frequently observed in practice, whereas blood bag labelling mistakes rarely occur during the labelling process itself.
The likelihood of such cognitive mistakes arising is an inherent and major disadvantage of the following devices intended to avoid such mistakes. For example, U.S. Pat. No. 5,314,421 issued May 24, 1994 to Leuenberger describes a microporous plastic film blood pack label which avoids wrinkling and thus distortion of its printed indicia. U.S. Pat. No. 3,698,383 issued Oct. 17, 1972 to Baucom describes combined elements including a patient identification band, having removable labels and a fastener, integrally combined with a pilot tube depending from a blood bag from which the band is ultimately separated. This system is used strictly to cross-identify, by means of printed indicia, a biological fluid and its recipient and fails to provide any physical impediments to mismatching the pilot tube with a patient cannula.
Other devices focus on preventing accidents by use of physical impediments, which do tend to limit the failure of use of cognitive skills which cause accidents. For example, U.S. Pat. No. 4,678,458 issued Jul. 7, 1987 to Fredeking describes an apparatus and method using a lock and key to avoid mistakes during plasmapheresis, which involves taking blood and then returning the red blood cells back to the same donor. The flow of returned blood cells is allowed only by using a unique key to unlock a lock box which controls a roller clamp interposed on a flexible tubing cannula between the blood bag and the donor patient. U.S. Pat. No. 5,125,920 issued Jun. 30, 1992 to Ishida is directed towards the prevention of mislabelling blood component bags at the time of blood donation (rather than towards prevention of misidentifying the bags at transfusion time), by providing several component bags interconnected by tubing for receiving blood. However, an inherent problem with such devices includes the inordinate amount of time necessary to operate the device thus tending to dedicate its use exclusively to autologous circumstances and teaching away from its use in emergency settings.
Finally, U.S. Pat. No. 4,150,673 issued Apr. 24, 1979 to Watt describes a blood bag having coded inlet-outlet fitments directed at preventing improper transfusions of bag contents. Like a child's peg and hole playset, a series of port fitments attached to the blood bag are coded according to various geometric shapes, which requires that only a correctly shaped hollow spike is allowed into the correctly coded port to permit puncture of the bag and thereby start flow of the fluid contained therein. FIG. 5 and FIG. 6 of the Watt patent show additional embodiments of the fitments and a brief accompanying description suggests that overlay fitments provided as a separate unit can be used to convert a bag having a conventional port to the coded system.
Although the simple Watt system does limit the inadvertent mismatch of ports and spikes of different shapes, it fails to teach the use of any one port as specifically matching a specific blood type (e.g. the square port is blood type B-). Thus, the chance of fatal error by providing mismatched blood is still high unless a consistent use or method is established wherein one type of port is used for one type of blood. Such a method is not taught.
Moreover, the variously configured structures of each port cause serious practical disadvantages to arise during use. Various mating configurations require that a multitude of pairs of parts be manufactured, and ultimately stored by the healthcare provider. Thus, depending on the frequency of need or if a sudden "run" on a particular blood type occurs, a mating part (the spike and attached infusion cannula) may become temporarily unavailable despite the availability of blood type and properly coded bag. Thus, to prepare for such contingencies, the provider must store an overabundance of each of the mating parts (cannulas having differently spiked ends) leading to unnecessary and increased costs. In an environment having limited storage space considerations, such as ambulances, such stock piling is highly impractical. Furthermore, the presence of multiple parts require added time to locate the properly stored part, such time often being unavailable to a health care provider in emergency situations.
The present invention provides a means by which all of these problems are overcome, the inherent structure of such means obviating the need to have excess storage for multiple parts and most importantly, preventing the inadvertent cross-matching of different blood types. None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.